# The AGNTCY Agent Directory Service: Architecture and Implementation

arXiv: https://arxiv.org/abs/2509.18787 · HTML: https://mlsanity.com/paper/2509.18787/

## Key facts

- Cited by 4 papers in the map (data through 14 Oct 2026).
- Placed in Agent threats, guardrails and governance, one of 16 directions in LLM agents and tool use.
- Builds on 5 of its 38 references that are in the map.
- First posted on arXiv 23 Sep 2025.

## Placed in

- LLM agents and tool use / [Agent threats, guardrails and governance](https://mlsanity.com/agents/agent-threats-guardrails-and-governance/)

## Builds on (most cited first, 5 of 5)

- [Beyond DNS: Unlocking the Internet of AI Agents via the NANDA Index and Verified AgentFacts](https://mlsanity.com/paper/2507.14263/) (2025)
- [Upgrade or Switch: Do We Need a Next-Gen Trusted Architecture for the Internet of AI Agents?](https://mlsanity.com/paper/2506.12003/) (2025)
- [Evolution of AI Agent Registry Solutions: Centralized, Enterprise, and Distributed Approaches](https://mlsanity.com/paper/2508.03095/) (2025)
- [Using the NANDA Index Architecture in Practice: An Enterprise Perspective](https://mlsanity.com/paper/2508.03101/) (2025)
- [NANDA Adaptive Resolver: Architecture for Dynamic Resolution of AI Agent Names](https://mlsanity.com/paper/2508.03113/) (2025)

## Built on by (most cited first, 4 of 4)

- [Toward a Safe Internet of Agents](https://mlsanity.com/paper/2512.00520/) (2025)
- [Agentic AI Governance and Lifecycle Management in Healthcare](https://mlsanity.com/paper/2601.15630/) (2026)
- [Usable Agent Discovery for Decentralized AI Systems](https://mlsanity.com/paper/2604.23080/) (2026)
- [Trade-offs in Decentralized Agentic AI Discovery Across the Compute Continuum](https://mlsanity.com/paper/2605.11839/) (2026)

## Abstract (arXiv)

The Agent Directory Service (ADS) is a distributed directory for the discovery of AI agent capabilities, metadata, and provenance. It leverages content-addressed storage, hierarchical taxonomies, and cryptographic signing to enable efficient, verifiable, and multi-dimensional discovery across heterogeneous Multi-Agent Systems (MAS). Built on the Open Agentic Schema Framework (OASF), ADS decouples capability indexing from content location through a two-level mapping realized over a Kademlia-based Distributed Hash Table (DHT). It reuses mature OCI / ORAS infrastructure for artifact distribution, integrates Sigstore for provenance, and supports schema-driven extensibility for emerging agent modalities (LLM prompt agents, MCP servers, A2A-enabled components). This paper formalizes the architectural model, describes storage and discovery layers, explains security and performance properties, and positions ADS within the broader landscape of emerging agent registry and interoperability initiatives.